A Recessive Resistance to Rice yellow mottle virus Is Associated with a Rice Homolog of the CPR5 Gene, a Regulator of Active Defense Mechanisms

RYMV2 is a major recessive resistance gene identified in cultivated African rice (Oryza glaberrima) which confers high resistance to the Rice yellow mottle virus (RYMV). We mapped RYMV2 in an approximately 30-kb interval in which four genes have been annotated. Sequencing of the candidate region in the resistant Tog7291 accession revealed a single mutation affecting a predicted gene, as compared with the RYMV-susceptible O. glaberrima CG14 reference sequence. This mutation was found to be a one-base deletion leading to a truncated and probably nonfunctional protein. It affected a gene homologous to the Arabidopsis thaliana CPR5 gene, known to be a defense mechanism regulator. Only seven O. glaberrima accessions showing this deletion were identified in a collection consisting of 417 accessions from three rice species. All seven accessions were resistant to RYMV, which is an additional argument in favor of the involvement of the deletion in resistance. In addition, fine mapping of a resistance quantitative trait locus in O. sativa advanced backcrossed lines pinpointed a 151-kb interval containing RYMV2, suggesting that allelic variants of the same gene may control both high and partial resistance.

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The Genetic Basis of High Resistance to Rice Yellow Mottle Virus (RYMV) in Cultivars of Two Cultivated Rice Species

Plant Disease ◽

10.1094/pdis.1999.83.10.931 ◽

1999 ◽

Vol 83 (10) ◽

pp. 931-935 ◽

Cited By ~ 59

Author(s):

M. N. Ndjiondjop ◽

L. Albar ◽

D. Fargette ◽

C. Fauquet ◽

A. Ghesquière

Keyword(s):

Genetic Basis ◽

Virus Isolate ◽

Mottle Virus ◽

F1 Hybrids ◽

Enzyme Linked Immunosorbent Assay ◽

Rice Yellow Mottle Virus ◽

Recessive Resistance ◽

Cultivated Rice ◽

Recessive Resistance Gene ◽

Yellow Mottle

Three cultivars of Oryza sativa (IR64, Azucena, and Gigante) and four cultivars of O. glaberrima (Tog5681, Tog5673, CG14, and SG329) were evaluated for their resistance to two isolates of rice yellow mottle virus (RYMV) by enzyme-linked immunosorbent assay (ELISA) and symptomatology. Cultivars Tog5681 and Gigante were highly resistant, and no symptoms were observed when either virus isolate was inoculated at 10 or 20 days postgermination and assayed by ELISA at 7, 14, 22, 35, 50, or 64 days postinoculation. Azucena showed a partial resistance, whereas the other cultivars were susceptible. Symptom appearance was associated with increase in ELISA absorbance in the systemically infected leaves. The best discrimination among the cultivars occurred when the plants were inoculated at 10 days postgermination. Crosses were made between the highly resistant (Gigante and Tog5681) and the susceptible (IR64) cultivars to determine the genetic basis of resistance to RYMV. Evaluation of F1 hybrids and interspecific progenies, as well as the segregation of resistance in F2 and F3 lines of the IR64 × Gigante cross, provided results consistent with the presence of a single recessive resistance gene common to Tog5681 and Gigante.

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Emergence of a resistance-breaking isolate of Rice yellow mottle virus during serial inoculations is due to a single substitution in the genome-linked viral protein VPg

Journal of General Virology ◽

10.1099/vir.0.81659-0 ◽

2006 ◽

Vol 87 (5) ◽

pp. 1369-1373 ◽

Cited By ~ 39

Author(s):

Eugénie Hébrard ◽

Agnès Pinel-Galzi ◽

Anne Bersoult ◽

Christelle Siré ◽

Denis Fargette

Keyword(s):

Infectious Clone ◽

Recessive Gene ◽

Mottle Virus ◽

Rice Yellow Mottle Virus ◽

Recessive Resistance ◽

Nucleotide Polymorphism ◽

Single Nucleotide ◽

Resistance Breaking ◽

The Family ◽

Yellow Mottle

The recessive gene rymv-1, responsible for the high resistance of Oryza sativa ‘Gigante’ to Rice yellow mottle virus (genus Sobemovirus), was overcome by the variant CI4*, which emerged after serial inoculations of the non-resistance-breaking (nRB) isolate CI4. By comparison of the full-length sequences of CI4 and CI4*, a non-synonymous mutation was identified at position 1729, localized in the putative VPg domain, and an assay was developed based on this single-nucleotide polymorphism. The mutation G1729T was detected as early as the first passage in resistant plants and was found in all subsequent passages. Neither reversion nor any additional mutation was observed. The substitution G1729T, introduced by mutagenesis into the VPg of an nRB infectious clone, was sufficient to induce symptoms in uninoculated leaves of O. sativa ‘Gigante’. This is the first evidence that VPg is a virulence factor in plants with recessive resistance against viruses outside the family Potyviridae.

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Direct Interaction Between the Rice yellow mottle virus (RYMV) VPg and the Central Domain of the Rice eIF(iso)4G1 Factor Correlates with Rice Susceptibility and RYMV Virulence

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-03-10-0073 ◽

2010 ◽

Vol 23 (11) ◽

pp. 1506-1513 ◽

Cited By ~ 38

Author(s):

Eugénie Hébrard ◽

Nils Poulicard ◽

Clément Gérard ◽

Oumar Traoré ◽

Hui-Chen Wu ◽

...

Keyword(s):

Molecular Mechanisms ◽

Direct Interaction ◽

Translation Initiation Factor ◽

Initiation Factor ◽

Mottle Virus ◽

Rice Yellow Mottle Virus ◽

Recessive Resistance ◽

In Planta ◽

Central Domain ◽

Yellow Mottle

The adaptation of Rice yellow mottle virus (RYMV) to recessive resistance mediated by the rymv1-2 allele has been reported as a model to study the emergence and evolution of virulent variants. The resistance and virulence factors have been identified as eukaryotic translation initiation factor eIF(iso)4G1 and viral genome–linked protein (VPg), respectively, but the molecular mechanisms involved in their interaction are still unknown. In this study, we demonstrated a direct interaction between RYMV VPg and the central domain of rice eIF(iso)4G1 both in vitro, using recombinant proteins, and in vivo, using a yeast two-hybrid assay. Insertion of the E309K mutation in eIF(iso)4G1, conferring resistance in planta, strongly diminished the interaction with avirulent VPg. The efficiency of the major virulence mutations at restoring the interaction with the resistance protein was assessed. Our results explain the prevalence of virulence mutations fixed during experimental evolution studies and are consistent with the respective viral RNA accumulation levels of avirulent and virulent isolates. Our results also explain the origin of the residual multiplication of wild-type isolates in rymv1-2–resistant plants and the role of genetic context in the poor adaptability of the S2/S3 strain. Finally, the strategies of RYMV and members of family Potyviridae to overcome recessive resistance were compared.

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Resistance of selected Oryza glaberrima landraces and their intra-specific breeding lines to Beninese Rice yellow mottle virus isolates

Crop Protection ◽

10.1016/j.cropro.2019.01.022 ◽

2019 ◽

Vol 119 ◽

pp. 172-176 ◽

Cited By ~ 4

Author(s):

Y. Agnoun ◽

I. Yelome ◽

M. Sie ◽

L. Albar ◽

A. Ghesquière ◽

...

Keyword(s):

Mottle Virus ◽

Oryza Glaberrima ◽

Rice Yellow Mottle Virus ◽

Breeding Lines ◽

Yellow Mottle ◽

Virus Isolates

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Resistance of Oryza sativa and Oryza glaberrima Genotypes to RBe24 Isolate of Rice Yellow Mottle Virus in Benin and Effects of Silicon on Host Response

The Plant Pathology Journal ◽

10.5423/ppj.oa.09.2020.0180 ◽

2021 ◽

Vol 37 (4) ◽

pp. 375-388

Author(s):

Vital Kouessi Sixte Anato ◽

Yves Agnoun ◽

Joèl Houndjo ◽

Aderonke Oludare ◽

Clement Agbangla ◽

...

Keyword(s):

Oryza Sativa ◽

Disease Incidence ◽

Mottle Virus ◽

Oryza Glaberrima ◽

Rice Yellow Mottle Virus ◽

Comprehensive Strategy ◽

Yellow Mottle ◽

Rice Genotypes ◽

Resistant Genotypes ◽

Screen House

Rice yellow mottle virus (RYMV) is the most harmful virus that affects irrigated and lowland rice in Africa. The RBe24 isolate of the virus is the most pathogenic strain in Benin. A total of 79 genotypes including susceptible IR64 (Oryza sativa) and the resistant TOG5681 (O. glaberrima) as checks were screened for their reactions to RBe24 isolate of RYMV and the effects of silicon on the response of host plants to the virus investigated. The experiment was a three-factor factorial consisting of genotypes, inoculation level (inoculated vs. non-inoculated), and silicon dose (0, 5, and 10 g/plant) applied as CaSiO3 with two replications and carried out twice in the screen house. Significant differences were observed among the rice genotypes. Fifteen highly resistant and eight resistant genotypes were identified, and these were mainly O. glaberrima. Silicon application did not affect disease incidence and severity at 21 and 42 days after inoculation (DAI); it, however, significantly increased plant height of inoculated (3.6% for 5 g CaSiO3/plant and 6.3% for 10 g CaSiO3/plant) and non-inoculated (1.9% for 5 g CaSiO3/plant and 4.9% for 10 g CaSiO3/plant) plants at 42 DAI, with a reduction in the number of tillers (12.3% for both 5 and 10 g CaSiO3/plant) and leaves (26.8% for 5 g CaSiO3/plant and 28% for 10 g CaSiO3/plant) under both inoculation treatments. Our results confirm O. glaberrima germplasm as an important source of resistance to RYMV, and critical in developing a comprehensive strategy for the control of RYMV in West Africa.

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